Liquid and air mixing gear pump

ABSTRACT

The air intake ports of a liquid and air sucking and mixing gear pump are put into communication with the atmosphere through a collecting tank or chamber, in which the small amounts of foamy liquid-and-air emulsion flowing out from said ports during the stopping time of the pump are collected, and from which the amounts of emulsion are again sucked back into the pump as soon as the pump operation is again started.

0 United States Patent 11 1 1111 3,764,238 Carpigiani Oct. 9, 1973 LIQUID AND AIR MIXING GEAR PUMP 3,628,893 12 1971 Carpigiani 418/15 [76] Inventor: Poerio C. Carpigiani, Anzola,

Emilia, Bologna, Italy Primary Examiner-William L. Freeh Filed: Jan. 1972 Attorney-Edwin E. Greigg [21] Appl. No.2 220,239

[57] ABSTRACT [30] F i A ll gl p i D m The air intake ports of a liquid and air sucking and Feb 3 197' "My 2469 A! mixing gear pump are put 1nto communication with the atmosphere through a collecting tank or chamber, [52] U 8 Cl 418/15 in which the small amounts of foamy liquid-and-air [51] In} .Cl 1c 1/08 emulsion flowing out from Said ports during the p [58] Fieid 418/15 ping time of the pump are collected, and from which the amounts of emulsion are again sucked back into [56] References Cited the pump as soon as the pump operation is again UNITED STATES PATENTS started 3,479,957 11/1969 Canman 418/15 2 Claims, 3 Drawing Figures Y PAIENIEBUBI ems SHEET 10F 2 LIQUID AND AIR MIXING GEAR PUMP BACKGROUND OF THE INVENTION This invention relates to the gear pumps for the feeding of liquid and air mixes, and in particular to a gear pump of the kind which comprises a pump casing, a pair ofintermeshing gears rotatably mounted inside the casing, a liquid intake duct terminating at a liquid intake port disposed in the casing at a position where the gears begin to move out of mesh, and for each gear an air intake port disposed to supply air to the teeth of the gear.

A pump of the above kind is described in more details in the United States Patent application Ser. No. 031,877 which issued as U.S. Pat. No. 3,628,893 on Dec. 21, I971.

It has been found that, during the stopping time of the above-mentioned pump, the pressure existing downstream of the pump tends to cause a small amount of foamy liquidand-air emulsion to flow out of both air intake ports. This foam flows down into the liquid feed vat and, in the long run, an excessively great amount of foam comes to be collected in the vat.

SUMMARY OF THE INVENTION According to the invention, the drawback as encountered in gear pumps of the above-mentioned type is obviated by providing, at the air intake ports, on their side open to the atmosphere, a small foam-collecting chamber or tank which is put into communication by one end with the atmosphere and, by its other end with the air intake ports of the pump, and into which tank the small amount of foam flowing out of the ports at the time the pump is being stopped can be collected, this foam amount being automatically sucked by the pump whenever the same is again started, but before the pump again begins to suck air.

Since the amount of foam being produced at every stopping of the pump is small, the tanks might have an extremely reduced volume, and might be formed in the pump casing itself, in the form of vertically, or almost vertically running cylindrical ducts communicating by their lower end with the air intake ports, and by their upper end with the atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the emulsifying pump according to the invention;

FIG. 2 is a cross-section of the same pump; and

FIG. 3 is a view with parts in section of the cover member of the pump as shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the pump as shown comprises a casing 1 housing the gears 2.

The casing 1 is closed at its front side by a cover 3 carrying the liquid mix intake pipe 4, the liquid-and-air emulsion delivery pipe 5, and the air intake ports 6 and 7.

In the prior art pumps of the kind referred to above, the ports are directly put into communication with the atmosphere. During the periods of time in which the pump is being temporary stopped, the downstream pressure within the pump promotes the outflow of a certain amount of foam from the air intake ports. The amount of foam is, per se, small. However, since the pump is being frequently stopped, and since in certain machines this stopping takes place after every dispensing of a few cubic centimeters of product, the total amount of foam being formed during one working day of the machine comes to be considerable. This foam is collected in the (not shown) underlying liquid mix feed vat. The accumulation of foam in the vat is objectionable from many viewpoints. Particularly, the foam, by floating, renders the aspect of the product in the feed vat rather unattractive. Additionally, the foam is not so well refrigerated as the liquid, since the air contained therewithin tends to render same heat insulating. Therefore, the foam can be more likely subject to alterations which might influence the taste of the whole product.

According to the present invention, in order to obviate the mentioned drawback, upstream of the air intake ports, small tanks are formed adapted to contain the amounts of foam being produced at every stopping of the pump. As shown in the drawings, and as better shown in FIG. 3 thereof, the tanks advantageously are in form of two ducts 8 and 9 formed in the body of the pump cover 3, which, from ports 6, 7, extend upwardly through all the remaining height of the cover, and freely open into, and communicate with the atmosphere.

The ducts are more than sufficient to contain the amount of foam being formed at every stopping of the pump, which amount, whenever the pump is again set in operation, is again sucked through ports 6 and 7, before that the ports will begin again to suck the air to be emulsified with the liquid being sucked through pipe 4.

Of course the present invention is not limited to the shown embodiment and although the small tanks have been shown as formed in the cover body itself, it is understood that the same might be similarly obtained by providing independent tubular members to be fitted onto ports 6 and 7, or by providing any other container member to be arranged upstream of ports 6 and 7.

I claim:

1. In a gear pump for the feeding of liquid-and-air mixes, which comprises a liquid intake port upstream of the region in which the pump gears are in mesh, a liquid-and-air emulsion delivery port downstream of the region in which the pump gears are in mesh, and two air intake ports, one for each one of the pump gears, to be disposed on the gear path between the liquid intake port and the emulsion delivery port, the improvement comprising a collecting chamber, and wherein said air intake ports are put into communication with the atmosphere through said collecting chamber.

2. A gear pump according to claim 1, wherein said collecting chamber is formed in the pump body itself and is constituted by a substantially vertically running tubular duct communicating at its lower end with each one of the intake ports and, at its top, with the atmosphere. 

1. In a gear pump for the feeding of liquid-and-air mixes, which comprises a liquid intake port upstream of the region in which the pump gears are in mesh, a liquid-and-air emulsion delivery port downstream of the region in which the pump gears are in mesh, and two air intake ports, one for each one of the pump gears, to be disposed on the gear path between the liquid intake port and the emulsion delivery port, the improvement comprising a collecting chamber, and wherein said air intake ports are put into communication with the atmosphere through said collecting chamber.
 2. A gear pump according to claim 1, wherein said collecting chamber is formed in the pump body itself and is constituted by a substantially vertically running tubular duct communicating at its lower end with each one of the intake ports and, at its top, with the atmosphere. 